Protein kinase C isoforms in rat kidney proximal tubule: acute effect of angiotensin II

Am J Physiol. 1995 Jul;269(1 Pt 1):C134-40. doi: 10.1152/ajpcell.1995.269.1.C134.


The present study examined the effect of phorbol esters, Ca2+, and angiotensin II (ANG II) on protein kinase C (PKC) isoforms in the rat proximal tubule. The immunoblot analysis of PKC isoforms of particulate and cytosolic fractions of proximal tubules revealed immunoreactive proteins when antibodies against PKC-alpha, -delta, -epsilon, and -zeta, but not -beta and -gamma were used. Phorbol dibutyrate (PDBU) induced the translocation of PKC-alpha, -delta, and -epsilon, whereas an inactive phorbol ester had no effect. PDBU and ionomycin increased particulate PKC specific activity from 0.67 +/- 0.09 to 1.56 +/- 0.18 and 0.96 +/- 0.04 pmol.microgram protein-1.2 min-1, respectively. ANG II (10(-7) M) induced a time-dependent increase in particulate PKC-alpha immunoreactivity observed after 2 min and maintained for 12 min. Particulate PKC-epsilon immunoreactivity increased after 4 min. Meanwhile, PKC-delta and -zeta were not modified by ANG II. Accordingly, ANG II elicited a rise in the specific activity of the particulate PKC, which increased to 0.89 +/- 0.09 pmol.micrograms protein-1.2 min-1 after 2 min. This was inhibited by a preincubation in the presence of 10(-5) M losartan, specific inhibitor of angiotensin subtype 1 receptors. These data indicate that PKC-alpha and -epsilon are potential candidates to regulate the activity of Na+/H+ and Na(+)-HCO3- transporters because they are translocated with a time course fitting with that of the reported effect of ANG II on those transporters.

MeSH terms

  • Angiotensin II / pharmacology*
  • Animals
  • Biological Transport / drug effects
  • Calcium / pharmacology
  • Diglycerides / pharmacology
  • Histones / metabolism
  • Isoenzymes / metabolism*
  • Kidney Tubules, Proximal / drug effects*
  • Kidney Tubules, Proximal / enzymology*
  • Phorbol 12,13-Dibutyrate / pharmacology
  • Phosphatidylserines / pharmacology
  • Phosphorylation
  • Protein Kinase C / metabolism*
  • Rats
  • Tissue Distribution


  • Diglycerides
  • Histones
  • Isoenzymes
  • Phosphatidylserines
  • Angiotensin II
  • Phorbol 12,13-Dibutyrate
  • Protein Kinase C
  • Calcium